School of Plant and Environmental Sciences, Virginia Polytechnic Institute and State University , Blacksburg , VA , USA.
Institute of Agricultural Environment and Resources, Shanxi Academy of Agricultural Sciences , Taiyuan , Shanxi , P.R. China.
Plant Signal Behav. 2019;14(10):e1651607. doi: 10.1080/15592324.2019.1651607. Epub 2019 Aug 12.
Plant hormones play an important role in plant adaptation to abiotic stress, but hormonal responses of cool-season turfgrass species to drought stress are not well documented. This study was to investigate responses of hormones and photosynthesis to drought stress and examine if drought stress - induced hormone alteration is associated with stress tolerance in kentucky bluegrass (KBG, L.). The grass was grown in a growth chamber for 6 weeks and then subjected to drought stress [40%-50% evapotranspiration (ET) replacement)] for 28 d. Drought stress caused cell membrane damage, resulting in decline in photosynthetic rate (Pn), chlorophyll content, and visual quality in KBG. Drought stressed grass had higher leaf abscisic acid (ABA), lower leaf -zeatin riboside (ZR), isopentenyl adenosine (iPA), and indole-3-acetic acid (IAA), but similar level of leaf gibberellin A4 (GA4) when compared to the control (well-watered). On average, drought stress treatment reduced leaf ZR by 59.1%, iPA by 50.4%, IAA by 26.7%, while increased ABA by 108.5% when compared to the control at the end of drought stress (28 d). The turf quality and photosynthetic rate was positively correlated with cytokinins and IAA, but negatively correlated with ABA and ABA/cytokinins (CK) ratio under drought stress. The results of this study suggest drought stress-induced injury to Kentucky bluegrass may be associated with hormonal alteration, and the plants with higher cytokinins and IAA and less ABA under drought stress may have better photosynthetic function and performance.
植物激素在植物适应非生物胁迫方面发挥着重要作用，但有关冷季草坪草对干旱胁迫的激素反应的资料并不多。本研究旨在探讨激素和光合作用对干旱胁迫的响应，并研究干旱胁迫诱导的激素变化是否与草坪草的耐旱性有关。将草坪草在生长室中生长 6 周，然后进行干旱胁迫（40%-50%的蒸腾蒸发量替代）28 天。干旱胁迫导致细胞膜损伤，导致草坪草的光合速率（Pn）、叶绿素含量和外观质量下降。与对照（充分浇水）相比，干旱胁迫下的草坪草叶片脱落酸（ABA）含量较高，玉米素核苷（ZR）、异戊烯腺嘌呤（iPA）和吲哚-3-乙酸（IAA）含量较低，而赤霉素 A4（GA4）含量相似。平均而言，与对照相比，干旱胁迫处理在干旱胁迫结束时（28 天）降低了叶片 ZR 59.1%、iPA 50.4%、IAA 26.7%，而 ABA 增加了 108.5%。在干旱胁迫下，草坪草的质量和光合速率与细胞分裂素和 IAA 呈正相关，与 ABA 和 ABA/细胞分裂素（CK）比值呈负相关。本研究结果表明，草坪草的干旱胁迫损伤可能与激素变化有关，干旱胁迫下细胞分裂素和 IAA 较高、ABA 较低的植物可能具有更好的光合功能和表现。
